// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.

#ifndef STORAGE_LEVELDB_UTIL_HISTOGRAM_H_
#define STORAGE_LEVELDB_UTIL_HISTOGRAM_H_

#include <string>

namespace leveldb {

class Histogram {
public:
    Histogram() {}
    ~Histogram() {}

    void Clear();
    void Add(double value);
    void Merge(const Histogram& other);

    std::string ToString() const;

private:
    enum { kNumBuckets = 154 };

    double Median() const;
    double Percentile(double p) const;
    double Average() const;
    double StandardDeviation() const;

    static const double kBucketLimit[kNumBuckets];

    double min_;
    double max_;
    double num_;
    double sum_;
    double sum_squares_;

    double buckets_[kNumBuckets];
};

}  // namespace leveldb

#endif  // STORAGE_LEVELDB_UTIL_HISTOGRAM_H_